Lens alignment apparatus

ABSTRACT

A lens alignment apparatus includes a main lens holding frame having a main lens secured thereto; an adjusting lens holding frame to which an adjusting lens to be aligned with the main lens is secured; at least one radial groove formed in one of adjacent end surfaces of the main lens holding frame and the adjusting lens holding frame; a centering hole, corresponding to the radial groove, formed in the other of the adjacent end surfaces of the main lens holding frame and the adjusting lens holding frame; and an alignment member including a centering pillar portion inserted in the centering hole and an aligning portion engaged in the radial groove, the aligning portion being provided with a plurality of pairs of parallel alignment surfaces having an identical width and different distances from the axis of the centering pillar portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens alignment apparatus forcorrecting disalignment of a lens.

2. Description of the Related Art

Various lens alignment apparatuses for aligning an optical axis of amain lens (lens group) with an optical axis of an adjusting lens (lensgroup) upon assembly are known, and have been made commercially viable.The basic concept of such prior art lens alignment apparatuses is tocontinuously adjust the position of the optical axis of the adjustinglens relative to the optical axis of the main lens in a stepless manner.In such a stepless type of lens alignment apparatus, the operator isfree to optionally select a desired adjustment position. However, lensproducts tend to have the same disalignment for each lot. Nevertheless,the operator must individually carry out an adjustment for each lensproduct to determine a correct position from different initialpositions. Therefore, such disalignment adjustment is complicated andrequires an increased amount of time. Moreover, the accuracy of theadjustment becomes irregular due to differences in the operator's skillor the quality of the lens products. Furthermore, once the lens assemblyis disassembled, it is practically impossible to reproduce the alignedstate thereof.

In view of the drawbacks of the prior art mentioned above, the presentinvention provides a lens alignment apparatus in which a lens alignmentcan be easily performed with a minimum number of operations and in ashort time.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a lens alignmentapparatus is provided, including a main lens holding frame having a mainlens secured thereto; an adjusting lens holding frame to which anadjusting lens to be aligned with the main lens is secured; at least oneradial groove formed in one of adjacent end surfaces of the main lensholding frame and the adjusting lens holding frame; a centering hole,corresponding to the radial groove, formed in the other of the adjacentend surfaces of the main lens holding frame and the adjusting lensholding frame; and an alignment member including a centering pillarportion inserted in the centering hole and an aligning portion engagedin the radial groove, the aligning portion being provided with aplurality of pairs of parallel alignment surfaces having an identicalwidth and different distances from the axis of the centering pillarportion.

It is desirable for the lens alignment apparatus to have a pair of theradial grooves provided at angular intervals of 90 degrees.

It is desirable for the centering hole of the main lens holding frameand the centering pillar portion of the alignment member to haveinterengageable polygonal shapes.

According to the above-described structure, a lens alignment can beeasily carried out by a minimum number of operations and the alignedstate can be easily reproduced.

In an embodiment, a lens alignment apparatus is provided, including amain lens holding frame having a main lens secured thereto; an adjustinglens holding frame to which an adjusting lens to be aligned with themain lens is secured; a plurality of radial grooves formed in one ofadjacent end surfaces of the main lens holding frame and the adjustinglens holding frame, the radial grooves being arranged on a common circlewhose center is located on an optical axis; a plurality of alignmentholes corresponding to the radial grooves, formed in the other of theadjacent end surfaces of the main lens holding frame and the adjustinglens holding frame, the alignment holes including at least one alignmentpin hole and at least one regular polygonal hole; at least one alignmentpin including a cylindrical pillar portion which is relatively rotatablyinserted in the alignment pin hole, and an eccentric cylindrical pillarportion which is relatively rotatably fitted in one of the radialgrooves, the eccentric cylindrical pillar portion being eccentric withrespect to the cylindrical pillar portion; and at least one alignmentmember including a centering pillar portion which can be inserted in theregular polygonal hole at different angular phases, and an aligningportion which can be engaged in another of the radial grooves regardlessof the angular phase with respect to the regular polygonal hole, thealigning portion being provided with a plurality of pairs of parallelalignment surfaces having an identical width and different distancesfrom the axis of the centering pillar portion.

It is desirable for the alignment pin hole and the regular polygonalhole to be identical regular-polygonal shaped holes.

It is desirable for each of the alignment pin and the alignment memberto be provided with a central insertion hole for a securing screw.

It is desirable for the radial grooves to include at least one radialthrough-groove in which the alignment pin is fitted and at least oneradial bottomed-groove in which the alignment member is fitted.

It is desirable for the lens alignment apparatus to have four of theradial grooves provided at angular intervals of 90 degrees, wherein oneof the radial grooves for the alignment pin and another of the radialgrooves for the alignment member are aligned along a straight linepassing through a center of one of the main lens holding frame and theadjusting lens holding frame.

It is desirable for the identical regular-polygonal shaped holes toinclude at least eight regular polygonal holes which are spaced at anequal angular intervals.

It is desirable for the alignment pin hole to be a circular hole.

According to the above-described structure, the lens alignment can beeasily carried out with a small number of operations.

The present disclosure relates to subject matter contained in JapanesePatent Application Nos. 2005-192555 and 2005-192556 (both filed on Jun.30, 2005) which are expressly incorporated herein by reference in theirentireties.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below in detail with referenceto the accompanying drawings in which:

FIG. 1 is an exploded front perspective view of a lens alignmentapparatus according to a first embodiment of the present invention;

FIG. 2 is an exploded rear perspective view of the lens alignmentapparatus according to the first embodiment of the present invention;

FIG. 3 is a sectional view of the lens alignment apparatus taken alongthe line III-III of FIG. 1, according to the first embodiment of thepresent invention;

FIG. 4 is a front elevational view of an alignment member of the lensalignment apparatus according to the first embodiment of the presentinvention;

FIG. 5 is a front elevational view of an adjusting lens holding frame inwhich two alignment members are engaged, in the lens alignment apparatusaccording to the first embodiment of the present invention;

FIG. 6 is a front elevational view of a main lens holding frame in whichtwo alignment members are inserted, in the lens alignment apparatusaccording to the first embodiment of the present invention;

FIG. 7 is a diagram showing the adjustment range of one alignment memberin the lens alignment apparatus according to the first embodiment of thepresent invention;

FIG. 8 is a diagram showing the adjustment range by two alignmentmembers in the lens alignment apparatus according to the firstembodiment of the present invention;

FIG. 9 is an exploded front perspective view of a lens alignmentapparatus according to a second embodiment of the present invention;

FIG. 10 is an exploded rear perspective view of the lens alignmentapparatus according to the second embodiment of the present invention;

FIG. 11 is a sectional view of the lens alignment apparatus taken alongthe line XI-XI in FIG. 9, according to the second embodiment of thepresent invention;

FIG. 12 is a sectional view of the lens alignment apparatus taken alongthe line XII-XII in FIG. 9, according to the second embodiment of thepresent invention;

FIG. 13 is a front elevational view of an alignment pin of the lensalignment apparatus according to the second embodiment of the presentinvention;

FIG. 14 is a front elevational view of an adjusting lens holding framein which an alignment member and an alignment pin are engaged, in thelens alignment apparatus according to the second embodiment of thepresent invention;

FIG. 15 is a front elevational view of the adjusting lens holding framein which two alignment members and alignment pins are engaged, in thelens alignment apparatus according to the second embodiment of thepresent invention;

FIG. 16 is a front elevational view of a main lens holding frame inwhich two alignment members and two alignment pins are inserted, in thelens alignment apparatus according to the second embodiment of thepresent invention;

FIG. 17 is a diagram showing the adjustment range of an alignment memberin the lens alignment apparatus according to the second embodiment ofthe present invention; and

FIG. 18 is a diagram showing the adjustment range by an alignment memberand an alignment pin in the lens alignment apparatus according to thesecond embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 3 show a first embodiment of a lens alignment apparatus10 according to the present invention. The lens alignment apparatus 10is adapted to carry out an adjustment to align the optical axis O of themain lens L1 with the optical axis O′ of the adjusting lens L2. The mainlens L1 which has a circular shape in a front elevation is held by acylindrical main lens holding frame 20, and the adjusting lens L2 whichhas a circular shape in a front elevation is held by a cylindricaladjusting lens holding frame 30. The main lens holding frame 20 and theadjusting lens holding frame 30 are made of a material which cannot beelastically deformed (e.g., hard plastic) when viewed macroscopically.It is assumed that the optical axis O of the main lens L1 is identicalto the axis of the main lens holding frame 20 and the optical axis O′ ofthe adjusting lens L2 is identical to the axis of the adjusting lensholding frame 30.

The main lens holding frame 20 has an annular end surface 20 a whichlies in a plane perpendicular to the optical axis O. The adjusting lensholding frame 30 has an annular end surface 30 a which lies in a planeperpendicular to the optical axis O′ and which faces the annular endsurface 20 a of the main lens holding frame 20. The adjusting lensholding frame 30 is secured to the main lens holding frame 20 bysecuring screws 40 after the adjusting lens L2 is aligned with the mainlens L1.

The end surface 20 a of the main lens holding frame 20 is provided withtwelve identical regular hexagonal holes (centering holes) 20 b whichare located on a circle, whose center is located on the optical axis O,and which are spaced at equal angular distances (30 degrees). Theregular hexagonal holes 20 b are each defined by three pairs of parallelplanes which are opposed to each other, one pair of the parallel planesextending in the radial directions of the main lens holding frame 20.The regular hexagonal holes 20 b have axes extending parallel with theoptical axis O and are provided at the inner end portions thereof withinternal threads (threaded holes 20 c) (FIG. 3) in which the securingscrews 40 can be screw-engaged.

The adjusting lens holding frame 30 is provided on its end surface 30 awith four radial grooves 31 at circumferential positions correspondingto the regular hexagonal holes 20 b. The radial grooves 31 are locatedon the same circle whose center is located on the optical axis O′ andare spaced at equal angular intervals (90 degrees). The radial grooves31 extend in the radial directions of the adjusting lens holding frame30. The inner ends of the radial grooves 31 are closed so as to eachform a U-shape thereat, and the outer ends thereof are open. The fourradial grooves 31 are provided at their center portions with screwinsertion holes 34.

Alignment members 50 are inserted between the regular hexagonal holes 20b of the main lens holding frame 20 and the radial grooves 31 of theadjusting lens holding frame 30 in order to adjust the position of theadjusting lens holding frame 30 in a plane perpendicular to the opticalaxis O (O′).

The alignment member 50 includes a regular hexagonal pillar portion(centering pillar portion) 51 which can be inserted in the regularhexagonal hole 20 b at different angular phases, an aligning portion 52which can be engaged in the radial grooves 31 at any predeterminedangular phase of the regular hexagonal pillar portion 51 with respect tothe regular hexagonal hole 20 b, and a flange portion 53 located betweenthe regular hexagonal pillar portion 51 and the aligning portion 52. Thealignment member 50 is provided on its center portion with a throughhole 54 in which the securing screw 40 is inserted and which has an axisidentical to the axis X of the regular hexagonal pillar portion 51.

The aligning portion 52 is provided with three pairs of alignmentsurfaces 52 a, 52 b and 52 c, as shown in FIG. 4, which can be engagedwith the radial grooves 31. The alignment surfaces 52 a, 52 b and 52 care parallel with corresponding sides (surfaces) of the regularhexagonal pillar portion 51. Each pair of opposed alignment surfaces 52a 52 b and 52 c are parallel surfaces separated by a distance 2A (eachpair of opposed alignment surfaces 52 a 52 b and 52 c defines the samewidth therebetween). The distances from the axis X of the regularhexagonal pillar portion 51 to each alignment surface for each pair ofalignment surfaces 52 a 52 b and 52 c is different.

Namely, the median of a pair of alignment surfaces 52 a of the aligningportion 52 is located on the axis X, i.e., the lengths of normal linesfrom the center axis X to the opposed alignment surfaces 52 a are “A”,which is exactly half of distance 2A. Therefore, when a pair of opposedalignment surfaces 52 a are engaged with (or abut against) the radialgroove 31 in the radial direction, no movement of the adjusting lensholding frame 30 relative to the main lens holding frame 20 in adirection perpendicular to the alignment surfaces 52 a, i.e., in adirection perpendicular to an extension of the radial groove 31 in whichthe aligning portion 52 is fitted (or the direction X or Y, or theopposite direction thereto as indicated in FIG. 5), occurs. In otherwords, the amount of adjustment or the displacement for alignment iszero.

The median of a pair of alignment surfaces 52 b of the aligning portion52 is deviated by α from the axis X. Namely, the lengths of the normallines from the axis X to the alignment surfaces 52 b are (A+α) and(A−α), respectively. Therefore, when a pair of opposed alignmentsurfaces 52 b are engaged with the radial groove 31, the adjusting lensholding frame 30 is moved by α, relative to the main lens holding frame20 in a direction perpendicular to the alignment surfaces 52 b (in thedirection X or Y or the opposite direction thereto, see FIG. 5). Notethat the amount of adjustment or the displacement for alignment is α.

The median of a pair of alignment surfaces 52 c of the aligning portion52 is deviated by 2α from the axis X. Namely, the lengths of the normallines from the axis X to the alignment surfaces 52 c are (A+2α) and(A−2α), respectively. Therefore, when a pair of opposed alignmentsurfaces 52 c are engaged with the radial groove 31, the adjusting lensholding frame 30 is moved by 2α, relative to the main lens holding frame20 in a direction perpendicular to the alignment surfaces 52 c (in thedirection X or Y or the opposite direction thereto, see FIG. 5). Notethat the amount of adjustment or the displacement for alignment is 2α.The flange portion 53 is provided with a cut-away portion 53 a whichserves as an indicia to indicate the angular phase (angular position) ofthe aligning portion 52 (see FIG. 4).

The flange portion 53 of the alignment member 50 and the washer 70determines the distance between the main lens holding frame 20 and theadjusting lens holding frame 30. Namely, when the adjusting lens holdingframe 30 is secured to the main lens holding frame 20 by the securingscrews 40, the flange portions 53 are disposed between the end surface30 a and the washers 70, and the washers 70 are disposed between theflange portions 53 and the end surface 20 a.

The principle of alignment using the alignment apparatus will bediscussed below. Four regular hexagonal holes 20 b which are spaced atan angular distance of 90 degrees are selected from the twelve regularhexagonal holes 20 b of the main lens holding frame 20, and the regularhexagonal pillar portions 51 of the alignment members 50 are inserted inthe selected regular hexagonal holes. FIG. 6 shows two of the alignmentmembers 50 inserted into two regular hexagonal holes 20 b. The angularphase of the regular pillar portions 51 of the alignment members 50, asa reference position, is determined so that the alignment surfaces 52 aof the regular hexagonal pillar portion 51 are oriented in the radialdirection of the main lens holding frame 20 and the cut-away portion 53a is located on the outer peripheral surface side of the main lensholding frame 20. The alignment surfaces 52 a of the aligning portions51 are fitted in the radial grooves 31 of the adjusting lens holdingframe 30. In this state, which corresponds to one of the adjustmentpositions, the alignment of the optical axis O of the main lens L1 withthe optical axis O′ of the adjusting lens L2 is checked with aconventional viewer (detector). If the alignment is complete (if theoptical axis O and the optical axis O′ are aligned), the adjusting lensholding frame 30 is secured to the main lens holding frame 20 by thesecuring screws 40.

In the secured position as mentioned above, for the sake of clarity, thealignment of the adjusting lens L2 (adjusting lens holding frame 30) inthe direction X (FIG. 5) will be explained below using one alignmentmember 50. In the initially secured position, if the optical axes arenot aligned, the alignment member 50 is detached and the angular phaseis changed by 60 degrees in the forward or reverse direction inaccordance with the observation result. Thereafter, the alignmentsurfaces 52 b or 52 c are oriented in the radial directions and theregular hexagonal portion 51 is fitted in the regular hexagonal hole 20b. If the alignment surfaces 52 b are selected, the angular adjustmentof α in the direction X is obtained and if the alignment surfaces 52 care selected, the angular adjustment of 2α is obtained.

Moreover, as a reference position, an angular phase can be selected inwhich the alignment surfaces 52 a of the regular hexagonal pillarportion 51 are oriented in the radial direction of the main lens holdingframe 20 and the cut-away portion 53 a is located on the innerperipheral surface side of the main lens holding frame 20. The angularphase is changed by 60 degrees in the forward or reverse direction inaccordance with the observation result. If the alignment surfaces 52 bare engaged in the radial grooves 31, the angular adjustment of α in thedirection opposite to the direction X is obtained. If the alignmentsurfaces 52 c are engaged in the radial grooves 31, the angularadjustment of 2α in the direction opposite to the direction X isobtained. Accordingly, it is possible to carry out the stepwiseadjustment in the direction X by the alignment members 50.

The adjustment in the direction Y can be equally carried out using thealignment members 50 whose positions are different by 90 degrees fromthe alignment members 50 that are used for the adjustment in thedirection X. The adjustments in the directions X and Y can be carriedout at one time using a pair of alignment members 50 which arediametrically opposed. Furthermore, it is possible to select theadjustment direction by optionally selecting the four regular hexagonalholes in which the alignment members 50 are to be inserted from amongthe twelve regular hexagonal holes 20 b of the main lens holding frame20.

FIGS. 7 and 8 show adjustment ranges in the X-Y directions in which theaxis of the adjusting lens holding frame 30 can be moved with respect tothe axis of the main lens holding frame 20. FIG. 7 shows the adjustmentrange of the adjusting lens holding frame 30 which is obtained by onealignment member 50 arranged on the axis X or Y while restricting themovement of the main lens holding frame 20 in the X-Y directions. FIG. 8shows the adjustment range of the adjusting lens holding frame 30 whichis obtained by two alignment members 50 arranged in the regularhexagonal holes 20 b located on the axes X and Y, respectively, whilerestricting the movement of the main lens holding frame 20 in the X-Ydirections. As can be understood from the foregoing, the optical axisposition of the adjusting lens holding frame 30 can be selectivelyadjusted by the use of two alignment members 50 which are inserted inthe two holes selected from the twelve regular hexagonal holes 20 b.Moreover, even if the alignment members 50 are not diametrically opposed(on the axes X and Y), the adjustment in a limited range can be carriedout by fitting two alignment members 50 in the optional regularhexagonal holes while restricting the movement of the main lens holdingframe 20. In the present invention, the adjustment in a limited rangecan be performed even by a single alignment member 50, as shown in FIG.7. If the alignment members 50 are fitted in the regular hexagonal holes20 b other than those located on the axes X and Y, the adjustmentdirection is inclined with respect to the directions X and Y, however,no change in the center takes place.

When lens products are mass produced, a specific disalignment tends tooccur for each lot. Therefore, the alignment can be simplified and thetime necessary for the alignment can be reduced by selecting in advancethe regular hexagonal holes 20 b in which the alignment members 50 areto be inserted and selecting in advance the alignment surfaces 52 a, 52b and 52 c of the alignment members 50. If the used alignment surfacesare remembered (recorded), the same adjusted state can be reproduced.The alignment surfaces 52 a, 52 b and 52 c that are being used can berecognized by the cut-away portions 53 a of the flange portions 53.

In the first embodiment of the present invention, the centering pillarportion of the alignment member 50 is made of the regular hexagonalpillar portion and, hence, the angular phase of the alignment member 50can be determined on the pillar portion 51 side. However, the angularphase of the alignment member 50 can be determined by the alignmentsurfaces 52 a, 52 b and 52 c, and accordingly, the regular hexagonalpillar portions 51 (and regular hexagonal holes 20 b) can be replacedwith circular pillar portions (and circular holes) which do not need tobe formed with high precision.

Note that although the four radial grooves 31 are provided in theillustrated embodiment, the alignment members 50 may be inserted in onlytwo (or one) radial grooves 31 and the remaining radial grooves can bemerely in the form of securing holes. Moreover, in theory, the greaterthe number of the regular hexagonal holes 20 b in which the alignmentmembers 50 are selectively fitted, the better. Therefore, twelve regularhexagonal holes 20 b are provided in the illustrated embodiment.However, in general, the practically acceptable number of regularhexagonal holes to provide a sufficient adjusting effect is at leasteight. Although the regular hexagonal holes 20 b are formed in the mainlens holding frame 20 and the radial grooves 31 are formed in theadjusting lens holding frame 30 in the illustrated embodiment, it ispossible to form the radial grooves 31 in the main lens holding frame 20and to form the regular hexagonal holes 20 b in the adjusting lensholding frame 30.

FIGS. 9 through 18 show a second embodiment of a lens alignmentapparatus 11 according to the present invention. The second embodimentdiffers from the first embodiment mainly in the following areas (A)through (C).

(A). The twelve regular hexagonal holes (polygonal holes/alignmentholes) 20 b formed in the end surface 20 a of the main lens holdingframe 20 are selectively used as alignment-member regular hexagonalholes 20 b(K) and alignment-pin regular hexagonal holes 20 b(P).

(B). Four radial grooves 31 formed in the end surface 30 a of theadjusting lens holding frame 30 include alignment-member radial grooves(bottomed grooves) 31(K) and alignment-pin radial through-grooves(through slots) 31(P). Each of the alignment-member radial grooves 31(K)is aligned with each respective alignment-pin radial through-grooves31(P) along a straight line passing through the center of the adjustinglens holding frame 30.

(C). The alignment member 50 and the alignment pin 60 are selectivelyinserted between the regular hexagonal holes 20 b of the main lensholding frame 20 and the alignment-member radial grooves 31(K) andalignment-pin radial through-grooves 31(P) of the adjusting lens holdingframe 30, so that the adjusting lens holding frame 30 can be moved foradjustment in a plane perpendicular to the optical axis O (O′).

The structure of the alignment member 50 is the same as that of thefirst embodiment. The aligning portion 52 of the alignment member 50 canbe engaged in the alignment-member radial groove 31(K), regardless ofthe angular phase of the regular hexagonal pillar portion 51 withrespect to the regular hexagonal hole 20 b. In the second embodiment,the components corresponding to those of the first embodiment aredesignated with like reference numerals.

As shown in FIG. 13, the alignment pin 60 includes a circular pillarportion 61 which can be inserted in the regular hexagonal hole 20 b soas to relatively rotate, an eccentric pillar portion 62 which iseccentric with respect to the circular pillar portion 61, and a flangeportion 63 located between the circular pillar portion 61 and theeccentric pillar portion 62. The alignment pin 60 is provided on itscentral portion with an insertion hole 64 through which the securingscrews 40 is inserted and which has an axis identical to the axis Z ofthe circular pillar portion 61.

The diameter of the eccentric pillar portion 62 corresponds to the widthof the alignment-pin radial through-groove 31(P) of the adjusting lensholding frame 30. The eccentric pillar portion 62 is provided, in theinner surface of the insertion hole 64, with a cut-away portion 62 awhich serves as an indicia indicating the angular phase (angularposition) of the eccentric pillar portion. The axis of the eccentricpillar portion 62 is deviated from the axis Z of the circular pillarportion 61 by an eccentricity d. The eccentricity d of the alignment pin60 is smaller than the minimum adjustment amount of the alignment member50. Accordingly, the rotation of the eccentric pillar portion 62(alignment pin 60) causes the adjusting lens holding frame 30 to finelymove in a direction (directions X and Y, or the opposite directionsthereof) (see FIGS. 15 and 16) perpendicular to an extension of thealignment-pin radial through-groove 31(P) of the adjusting lens holdingframe 30 in which the alignment pin 60 is inserted.

The flange portion 53 of the alignment member 50 and the washer 70, andthe flange portion 63 of the alignment pin 60 and the washer 70 definethe frame distance between the main lens holding frame 20 and theadjusting lens holding frame 30. Namely, when the adjusting lens holdingframe 30 is secured to the main lens holding frame 20 by the securingscrews 40, the flange portion 53 (flange portion 63) is located betweenthe end surface 20 a and the end surface 30 a and the washer 70 islocated between the flange portion 53 (flange portion 63) and the endsurface 20 a.

The principle of alignment using the alignment apparatus 11 will bediscussed below. Four regular hexagonal holes 20 b in which the twoalignment members 50 and the two alignment pins 60 are to be insertedare selected from the twelve regular hexagonal holes 20 b of the mainlens holding frame 20. The regular hexagonal pillar portions 51 of thealignment members 50 are inserted in the selected alignment-memberregular hexagonal holes 20 b(K), and the pillar portions 61 of thealignment pins 60 are inserted in the selected alignment-pin regularhexagonal holes 20 b(P). The angular phase of the regular pillarportions 51 of the alignment members 50 is determined so that thealignment surfaces 52 a of the regular hexagonal pillar portion 51 areoriented in the radial direction of the main lens holding frame 20, as areference position, and the cut-away portion 53 a is located on theouter peripheral surface side of the main lens holding frame 20. Thealignment surfaces 52 a of the aligning portions 51 are fitted in thealignment-member radial grooves 31(K) of the adjusting lens holdingframe 30, and the eccentric pillar portions 62 of the alignment pins 60are fitted in the alignment-pin radial through-grooves 31(P). In thisstate, which corresponds to one of the possible adjustment positions,the alignment of the optical axis O of the main lens L1 with the opticalaxis O′ of the adjusting lens L2 is checked with a conventional viewer(detector). In this state, fine adjustment can be performed by rotatingthe alignment pin 60. The adjusting lens holding frame 30 is secured tothe main lens holding frame 20 by the securing screws 40 upon theoptical axes O and O′ being aligned via the fine adjustment.

In the above-described secured position, the alignment of the adjustinglens L2 (adjusting lens holding frame 30) in the direction X (FIG. 5)carried out by only one alignment member 50 and only one alignment pin60, for the sake of clarity, is shown in FIG. 14 by way of example. Inthe initially secured position, if the optical axes O and O′ are notaligned, the alignment member 50 is detached and the angular phase ischanged by 60 degrees in the forward or reverse direction in accordancewith the observation result. Thereafter, the alignment surfaces 52 b or52 c are oriented in the radial directions and the regular hexagonalpillar portion 51 is fitted in the regular hexagonal hole 20 b. If thealignment surfaces 52 b are selected, the angular adjustment of a in thedirection X is obtained and if the alignment surfaces 52 c are selected,the angular adjustment of 2α is obtained.

Moreover, an angular phase can be selected as a reference position inwhich the alignment surfaces 52 a of the regular hexagonal pillarportion 51 are oriented in the radial direction of the main lens holdingframe 20 and the cut-away portion 53 a is located on the innerperipheral surface side of the main lens holding frame 20. The angularphase is changed by 60 degrees in the forward or reverse direction inaccordance with the observation result. If the alignment surfaces 52 bare engaged in the radial grooves 31, the angular adjustment of α in thedirection opposite to the direction X is obtained. If the alignmentsurfaces 52 c are engaged in the radial grooves 31, the angularadjustment of 2α in the direction opposite to the direction X isobtained.

Consequently, after the stepwise adjustment by the alignment members 50is achieved, the rotation of the alignment pins 60 causes a fineadjustment in the direction X. Furthermore, it is possible to select theadjustment direction by optionally selecting two regular hexagonal holesin which the alignment members 50 and the alignment pins 60 are to beinserted from among the twelve regular hexagonal holes 20 b of the mainlens holding frame 20.

FIGS. 15 and 16 show an adjustment by two alignment members 50 and twoalignment pins 60 which are arranged in two orthogonal directions. Thetwo alignment members 50 are spaced at an angular distance of 90 degreesand the alignment pins 60 are diametrically opposed to the respectivealignment members 50. Thus, the adjustment lens holding frame 30 can bemoved relative to the main lens holding frame 20 within the range of 0to 2α in the direction X, and 0 to 2α in the direction Y, by the twoalignment members 50. Thereafter, a fine adjustment in the directions Xand Y can be carried out by rotating the two alignment pins 60.

FIGS. 17 and 18 show adjustment ranges in the X-Y directions in whichthe axis of the adjusting lens holding frame 30 can be moved withrespect to the axis of the main lens holding frame 20. FIG. 17 shows theadjustment range of the adjusting lens holding frame 30 which isobtained by two alignment member 50 arranged in the regular hexagonalholes 20 b on the axes X and Y, while restricting the movement of themain lens holding frame 20 in the X-Y directions. FIG. 18 shows theadjustment range of the adjusting lens holding frame 30 which isobtained by two alignment members 50 and the two alignment pins 60,arranged in the regular hexagonal holes 20 b located on the axes X andY, respectively, while restricting the movement of the main lens holdingframe 20 in the X-Y directions.

As can be understood from the foregoing, the optical axis position ofthe adjusting lens holding frame 30 can be adjusted in all directions bya combination of the two alignment members 50 and the two alignment pins60, arranged in orthogonal directions. However, an adjustment describedwith reference to FIG. 15 can be achieved by one alignment member 50 andone alignment pin 60. Moreover, even if the alignment member 50 and thealignment pin 60 are not aligned on the axis X or Y, an adjustment in alimited range can be carried out by fitting the alignment member 50 andthe alignment pin 60 in the optional regular hexagonal holes 20 b whilerestricting the movement of the main lens holding frame 20. Namely, inthe present invention, an adjustment in a limited range can be performedeven by a single alignment member 50 and a single alignment pin 60 whichare not aligned along a straight line.

Accordingly, alignment can be simplified and the time necessary for thealignment to be carried out can be reduced by selecting in advance theregular hexagonal holes 20 b in which the alignment members 50 and thealignment pins 60 are to be inserted, and selecting in advance thealignment surfaces 52 a, 52 b and 52 c of the alignment members 50. Thealignment surfaces 52 a, 52 b and 52 c that are used can be recognized(remembered) by the cut-away portion 53 a of the flange portion 53.Likewise, the angular position of the alignment pins 60 can berecognized (remembered) by the cut-away portion 62 a.

Among the regular hexagonal holes 20 b, the alignment-pin regularhexagonal holes 20 b(P) in which the alignment pins 60 are inserted canbe replaced with circular holes. However, if the alignment-pin regularhexagonal holes 20 b(P) are used, as in the illustrated embodiment, theholes for the alignment pins can be commonly used for the alignmentmembers 50. Moreover, in theory, the greater the number of regularhexagonal holes 20 b, the better. However, in practice, at least eightregular hexagonal holes are provided. Although the regular hexagonalholes 20 b are formed in the main lens holding frame 20 and the radialgrooves 31 are formed in the adjusting lens holding frame 30 in theillustrated embodiment, it is possible to form the radial grooves 31 inthe main lens holding frame 20 and to form the regular hexagonal holes20 b in the adjusting lens holding frame 30. The regular hexagonalpillar portion 51 of the alignment member 50 can be replaced with acircular pillar. In the case where the regular hexagonal pillar portion51 of the alignment member 50 can is replaced with a circular pillar,the circular pillar does not need to be formed with high precision.

Obvious changes may be made in the specific embodiments of the presentinvention described herein, such modifications being within the spiritand scope of the invention claimed. It is indicated that all mattercontained herein is illustrative and does not limit the scope of thepresent invention.

1. A lens alignment apparatus comprising: a main lens holding framehaving a main lens secured thereto; an adjusting lens holding frame towhich an adjusting lens to be aligned with the main lens is secured; atleast one radial groove formed in one of adjacent end surfaces of themain lens holding frame and the adjusting lens holding frame; acentering hole, corresponding to said radial groove, formed in the otherof said adjacent end surfaces of the main lens holding frame and theadjusting lens holding frame; and an alignment member including acentering pillar portion inserted in said centering hole and an aligningportion engaged in said radial groove, said aligning portion beingprovided with a plurality of pairs of parallel alignment surfaces havingan identical width and different distances from the axis of thecentering pillar portion.
 2. The lens alignment apparatus according toclaim 1, comprising a pair of said radial grooves provided at angularintervals of 90 degrees.
 3. The lens alignment apparatus according toclaim 1, wherein the centering hole of the main lens holding frame andthe centering pillar portion of the alignment member haveinterengageable polygonal shapes.
 4. A lens alignment apparatuscomprising: a main lens holding frame having a main lens securedthereto; an adjusting lens holding frame to which an adjusting lens tobe aligned with the main lens is secured; a plurality of radial groovesformed in one of adjacent end surfaces of the main lens holding frameand the adjusting lens holding frame, said radial grooves being arrangedon a common circle whose center is located on an optical axis; aplurality of alignment holes corresponding to said radial grooves,formed in the other of said adjacent end surfaces of the main lensholding frame and the adjusting lens holding frame, said alignment holesincluding at least one alignment pin hole and at least one regularpolygonal hole; at least one alignment pin including a cylindricalpillar portion which is relatively rotatably inserted in said alignmentpin hole, and an eccentric cylindrical pillar portion which isrelatively rotatably fitted in one of said radial grooves, saideccentric cylindrical pillar portion being eccentric with respect tosaid cylindrical pillar portion; and at least one alignment memberincluding a centering pillar portion which can be inserted in saidregular polygonal hole at different angular phases, and an aligningportion which can be engaged in another of said radial groovesregardless of the angular phase with respect to said regular polygonalhole, said aligning portion being provided with a plurality of pairs ofparallel alignment surfaces having an identical width and differentdistances from the axis of the centering pillar portion.
 5. The lensalignment apparatus according to claim 4, wherein said alignment pinhole and said regular polygonal hole are identical regular-polygonalshaped holes.
 6. The lens alignment apparatus according to claim 4,wherein each of said alignment pin and said alignment member is providedwith a central insertion hole for a securing screw.
 7. The lensalignment apparatus according to claim 4, wherein said radial groovescomprise at least one radial through-groove in which said alignment pinis fitted and at least one radial bottomed-groove in which saidalignment member is fitted.
 8. The lens alignment apparatus according toclaim 4, comprising four of said radial grooves provided at angularintervals of 90 degrees, wherein one of said radial grooves for saidalignment pin and another of said radial grooves for said alignmentmember are aligned along a straight line passing through a center of oneof the main lens holding frame and the adjusting lens holding frame. 9.The lens alignment apparatus according to claim 5, wherein saididentical regular-polygonal shaped holes comprise at least eight regularpolygonal holes which are spaced at an equal angular intervals.
 10. Thelens alignment apparatus according to claim 4, wherein said alignmentpin hole comprises a circular hole.